Blending powders with liquids is a fairly common operation in the food processing industry. The powder may simply be added to a holding tank containing the liquid, and if desired the blend may be agitated, but this method leaves unsolved the problem of undissolved powder for difficult to dissolve ingredients.
U.S. Pat. No. 3,606,270 teaches a centrifugal pump which is modified to serve as a continuous powder blender. The impeller of the pump has a recessed eye portion of substantial depth in the top thereof, and the liquid and particulate material which are to be blended are both delivered together into the eye of the impeller. However; in an industrial application the blender taught in this patent was determined not to be as efficient as the blender disclosed herein because the pumping action of the mixer is significantly reduced and therefore its ability to discharge highly viscous slurries is impaired. Therefore this prior art apparatus needs an additional discharge pump and screen for higher viscosity or solid containing slurries.
The above mentioned shortcomings of the continuous powder mixer taught in U.S. Pat. No. 3,606,270 are recognized in U.S. Pat. No. 4,850,704. The solution taught in this later patent a two stage blender wherein the first stage is like the blender taught in U.S. Pat. No. 3,606,270 and the second stage receives the mixture discharged from the first stage and then discharges the mixture at a relatively high discharge pressure,
It is thus apparent that the need exists for an improved apparatus suitable for use in the food processing industry for blending a powder and a liquid.
There is provided in accordance with the present invention an apparatus which has the capacity to satisfactorily blend a liquid with a powder and pump the resultant viscous slurry in a single stage operation.